The Congress of the United States in the Clean Air Act of 1968 has specified certain limiting exhaust gas emission levels for internal combustion engines. The deleterious effect of air pollution on personal health and on the nation's ecology is a matter of common knowledge and concern and it is now a matter of public record that nitrous oxide, nitrogen dioxide, carbon monoxide and unburned hydrocarbon emission control, by use of post-combustion or exhaust gas recirculatory and/or catalytic devices connected to the exhaust pipe, is the direction that research on pollution control is presently taking. Such automotive accessory devices are expensive in the first cost and costly to maintain.
The problem of controlling nitrous oxide, nitrogen oxide, carbon monoxide and hydrocarbon emission at the source of formation, rather than by expensive catalytic devices connected to the exhaust pipe, is primarily one of lowering the peak cyclical combustion temperature at the flame front in the combustion chamber by stoichiometric combustion in lean fuel-air ratios for purposes of reducing the nitrous oxide and nitrogen dioxide formation, as well as completing combustion therein of the hydrocarbons and the carbon monoxide to harmless carbon dioxide and water by oxidation promotion, as disclosed in my prior co-pending applications.
The result of governmental agency regulation activity is that the industry has literally been placed on the horns of a dilemma. It has had to choose between (1) lowering the carbon monoxide, unburned hydrocarbon and nitrous oxide emission from its engines by improved engine carburetion, manifold distribution and borderline misfire engine operation at very lean fuel-air ratios, or (2) lowering the nitrous oxide and nitrogen dioxide emission therefrom by running the engines at richer, smoother-running mixtures and eliminating the consequent high carbon monoxide and unburned hydrocarbons by the use of post-combustion or exhaust gas recirculatory and/or platinum catalytic devices, or (3) running the engines at slightly less rich mixtures for better economy in miles per gallon and then meeting the stiff 90% reduction in nitrous oxide and nitrogen dioxide emission requirement, and the carbon monoxide and hydrocarbon emission requirement, by suitable catalytic devices. Needless to say, with regard to (2) and (3), such devices are expensive in the first instance and costly to maintain.
The mixture of fuel and air used as the working medium in an internal combustion engine is subject to chemical, thermal and mechanical changes during the course of its passage through the engine. As a first approximation the commonly known "Air Cycle" is presumed to use air as the working medium. Modification of this cycle to take into consideration the special characteristics of combustible dry-vapor fuel air mixtures and their composition products gives the well-known "Fuel-Air Cycle." The "Fuel-Air Cycle" becomes the "Actual Cycle" when it is modified to account for combustion losses, time losses, direct heat losses and leakage. The useful work left after the friction losses are subtracted from the work of the "Actual Cycle" determines the work output of the engine.
At a constant compression ratio, the dry-vapor "Fuel-Air Cycle" efficiency fails very rapidly because of incomplete utilization of fuel as the fuel-air ratio increases beyond the chemically-correct ratio. As mixtures become leaner than chemically correct, the temperatures of combustion and expansion become lower and the losses due to high specific heat and to incomplete chemical combination are correspondingly reduced so that there is an improvement in efficiency with decreasing fuel-air ratio which approaches air-cycle efficiency as the amount of fuel used becomes extremely small compared to the amount of air used. With a very low fuel-air ratio, the medium would consist, substantially, of air throughout the cycle, and since the temperature range would be small, the air would behave very nearly as a perfect gas. The air-cycle efficiency thus constitutes a limit which the efficiency of the dry-vapor fuel-air cycle approaches as the fuel-air ratio leans out. In practice there is, however, a limiting fuel-air ratio below which stable combustion cannot be sustained in dry-vapor fuel-air mediums. Also, there are additional losses in efficiency in the "actual cycle" due to excessively slow combustion with lean mixtures.
There is thus an established need for a means to accelerate and sustain stable combustion of dry-vapor fuel-air mixtures below current low lean limit fuel-air ratios if greater fuel-air cycle and actual cycle efficiencies than currently experienced are to be realized. It is the object of my invention to meet this need.